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Ship behavior prediction via trajectory extraction-based clustering for maritime situation awareness

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Journal of Ocean Engineering and Science 2022年第1期7卷 1-13页

作者： Brian Murray LokukalugePrasad perera UiT The Arctic University of Norway TromsøNorway

This study presents a method in which historical AIS data are used to predict the future trajectory of a se-lected *** is facilitated via a system intelligence-based approach that can be subsequently utilized to provide enhanced situation awareness to navigators and future autonomous ships,aiding proactive col-lision *** evaluating the historical ship behavior in a given geographical region,the method applies machine learning techniques to extrapolate commonalities in relevant trajectory *** commonalities represent historical behavior modes that correspond to the possible future behavior of the selected ***,the selected vessel is classified to a behavior mode,and a trajectory with respect to this mode is *** is achieved via an initial clustering technique and subsequent tra-jectory *** extracted trajectories are then compressed using the Karhunen-Loéve transform,and clustered using a Gaussian Mixture *** approach in this study differs from others in that tra-jectories are not clustered for an entire region,but rather for relevant trajectory *** such,the extracted trajectories provide a much better basis for clustering relevant historical ship behavior modes.A selected vessel is then classified to one of these modes using its observed *** predic-tions are facilitated using an enhanced subset of data that likely correspond to the future behavior of the selected *** method yields promising results,with high classification accuracy and low prediction ***,vessels with abnormal behavior degrade the results in some situations,and have also been discussed in this study.

关键词： Maritime situation awareness Ship navigation Trajectory prediction Collision avoidance Machine learning Unsupervised learning AIS

Demonstration of Far-Infrared GaAs/AlGaAs Quantum Well Photodetectors for Broadband Wavelength Detection

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Chinese Physics Letters 2000年第12期17卷 921-923页

作者： SHEN Wen-Zhong perera A.G.U Department of Applied Physics Shanghai Jiao Tong UniversityShanghai 200030 National Laboratory for Infrared Physics Shanghai Institute of Technical PhysicsShanghai 200083 Department of Physics and Astronomy Georgia State UniversityAtlantaGA 30303USA

We discuss the realization of broadband wavelength detection by demonstrating the longest cutoff wavelength(λc=28.6μm)far-infrared GaAs/AIGaAs quantum well infrared photodetectors(QWIPs).The responsivity is comparable to that of mid-infrared GaAs/AIGaAs and InGaAs/GaAs QWIPs,with a responsivity of 0.265 A/W and detectivity of 3.4x109 ***1/2/W at the peak wavelength of 26.9μm at *** on the temperature-dependent dark current and response results,it is expected that similar performance can be obtained at least up to 20 *** ways to expand the wavelength coverage are also addressed.

关键词： GaAs/AlGaAs Infrared Quantum

Recovery of Nitrogen and Phosphorous as Struvite From Swine Waste Biogas Digester Effluent

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Biomedical and Environmental Sciences 2007年第5期20卷 343-350页

作者： P. W. ANTON perera College of Environmental and Resource Sciences Zhejiang University

Objective To investigate the feasibility of nitrogen and phosphorus recovery from swine waste biogas digester effluent and the effects of pH and NH4^＋： Mg2^＋： PO4^3- molar ratio on its precipitation. Methods Precipitation experiments with swine waste biogas digester effluent were conducted at pH 7.5, 8.0, 8.5, and 9.0 together with NH4^＋： Mg^2＋： PO4^3- molar ratios 1： 0.2： 0.08, 1： 1： 1, and 1： 1.5： 1.5. Chemical and X-ray diffraction （XRD） analysis were done to determine the composition of the precipitate. Results The highest removal and recovery of NH4^＋ and PO4^3- were achieved at pH 9.0 in each experiment. The elevation of pH to 9.0 alone could decrease the initial PO4^3- concentration from 42 mg L^-1 to 4.7 mg L-1 and 89.2% PO4^3- recovery was achieved. The pH-molar ratio combination 9.0-1： 1.5： 1.5 effected 76.5% NH4^＋ and 68.5% PO4^3- recovery. The molar ratio of 1： 1： 1 together with pH elevation to 9.0 was determined to be the optimum combination for both NH4＋ and PO4^3- removal as it recovered over 70% and 97% of the initial NH4^＋ and PO4^3-, respectively. Conclusions Nitrogen and phosphorus can be recovered from biogas digester effluent as struvite.

关键词： Phosphate recovery Ammonium nitrogen recovery Biogas Struvite Swine waste

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COVID-19-induced anxiety,depression and stress among healthcare professionals in Sri Lanka

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Asian Pacific Journal of Tropical Medicine 2022年第11期15卷 485-495,I0010-I0012页

作者： Lahiru Udayanga Ayesha perera Lakchani Dissanayaka Department of Bio-Systems Engineering Faculty of Agriculture and Plantation ManagementWayamba University of Sri LankaMakanduraSri Lanka Nawaloka Medicare GampahaSri Lanka

Objective:To assess the degree of anxiety,depression and stress due to the COVID-19 epidemic among healthcare professionals in Sri ***:Healthcare professionals from 6 selected government and private hospitals located in Gampaha District were recruited for the *** socio-demographic factors,knowledge and attitudes of healthcare professionals on COVID-19 was collected through a self-administered questionnaire,while Depression,Anxiety and Stress Scale score was used to assess the psychological *** statistics and binary logistic regression techniques were used for data ***:Totally 324 healthcare professionals were included and the respondents had a high overall level of knowledge towards ***-five percent of the respondents had different levels of anxiety,while 10.8%had mild depression,and 4.6%had moderate ***,40.4%of the respondents had mild stress,and 11.1%had moderate *** people(20-35 years),medical laboratory technologist and nursing officer,being quarantined,having a SARS-CoV-2-infected family member,involvement in COVID-19 patient care,and limited availability of personal protection equipment,were recognized as significant risk factors associated with anxiety,depression and ***:The healthcare professionals are high-risk groups to experience psychological impacts from *** monitoring and implementing appropriate intervention activities and provision of counseling support are highly recommended.

关键词： COVID-19 Anxiety,depression and stress Healthcare providers Sri Lanka

Porosity of bimodal and trimodal sediment mixtures

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International Journal of Sediment Research 2022年第2期37卷 258-271页

作者： Chamil perera Weiming Wu Ian Knack Department of Civil and Environmental Engineering Clarkson University

This study focuses on the prediction of the porosity of nonuniform sediment mixtures,considering the effects of particle packing.A random particle packing model has been developed for the porosity of bimodal mixtures by extending the existing random particle filling *** in the developed model are calibrated by fitting the model to measured data for a variety of bimodal mixtures,including spherical glass particles,rounded quarry grains,and natural *** model coefficients are found to be functions of the diameter ratio of coarse and fine particles,separately for spherical glass particles and natural sediments due to differences in particle *** bimodal mixture model is then extended to trimodal particle mixtures in three approaches:two based on serial packing and one based on random *** models are tested against experimental data of six trimodal mixtures with spherical glass *** results show that the random packing model and the fine-medium-coarse particle serial packing model predict well the observed trimodal mixture porosities.

关键词： Porosity Particle filling Particle packing Bimodal mixture Trimodal mixture

SIMAP500: A novel risk score to identify recipients at higher risk of hepatocellular carcinoma recurrence following liver transplantation

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World Journal of Transplantation 2024年第3期14卷 132-143页

作者： Amr Alnagar Nekisa Zakeri Konstantinos Koilias Rosemary E Faulkes Rachel Brown Owen Cain M Thamara P R perera Keith J Roberts Rebeca Sanabria-Mateos David C Bartlett Yuk Ting Ma Shivan Sivakumar Shishir Shetty Tahir Shah Bobby V M Dasari Department of HBP and Liver Transplantation Surgery Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Centre for Liver Research Institute of Biomedical ResearchBirmingham B152TTUnited Kingdom Department of Hepatology Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Department of Pathology University Hospitals Birmingham NHS Foundation TrustBirmingham B152GWUnited Kingdom Department of Oncology Queen Elizabeth HospitalUniversity Hospitals of BirminghamBirmingham B152GWUnited Kingdom

BACKGROUND Recurrence of hepatocellular carcinoma(HCC)following liver transplantation(LT)has a devastating influence on recipients’survival;however,the risk of recur-rence is not routinely *** stratification is vital with a long LT waiting time,as that could influence the recurrence despite strict listing *** This study aims to identify predictors of recurrence and develop a novel risk pre-diction score to forecast HCC recurrence following *** A retrospective review of LT for HCC recipients at University Hospitals Bir-mingham between July 2011 and February *** and multivariate analyses were performed to identify recurrence predictors,based on which the novel SIMAP500(satellite nodules,increase in size,microvascular invasion,AFP>500,poor differentiation)risk score was *** 234 LTs for HCC were performed with a median follow-up of 5.3 *** developed in 25 patients(10.7%).On univariate analyses,RETREAT score>3,α-fetoprotein(AFP)at listing 100-500 and>500,bridging,increased tumour size between imaging at the listing time and explant histology,increase in the size of viable tumour between listing and explant,presence of satellite nodules,micro-and macrovascular invasion on explant and poor differentiation of tumours were significantly associated with recurrence,based on which,the SIMAP500 risk score is *** SIMAP500 demonstrated an excellent predictive ability(c-index=0.803)and outper-formed the RETREAT score(c-index=0.73).SIMAP500 is indicative of the time to disease *** SIMAP500 risk score identifies the LT recipients at risk of HCC *** stratification allows patient-centric post-transplant surveillance *** validation of the score is recommended.

关键词： Liver transplantation Hepatocellular carcinoma Recurrence Survival

Towards climate resilient urban energy systems: a review

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National Science Review 2021年第3期8卷 159-176页

作者： Vahid M.Nik A.T.D.perera Deliang Chen Division of Building Physics Department of Building and Environmental Technology Lund University Institute for Future Environments(IFE) Queensland University of Technology(QUT) Regional Climate Group Department of Earth SciencesUniversity of Gothenburg Division of Building Technology Department of Architecture and Civil Engineering Chalmers University of Technology Solar Energy and Building Physics Laboratory(LESO-PB) Ecole Polytechnique Federale de Lausanne(EPFL) Urban Energy Systems Laboratory

Climate change and increased urban population are two major concerns for *** towards more sustainable energy solutions in the urban context by integrating renewable energy technologies supports decarbonizing the energy sector and climate change mitigation.A successful transition also needs adequate consideration of climate change including extreme events to ensure the reliable performance of energy systems in the long *** review provides an overview of and insight into the progress achieved in the energy sector to adapt to climate change,focusing on the climate resilience of urban energy *** state-of-the-art methodology to assess impacts of climate change including extreme events and uncertainties on the design and performance of energy systems is described and *** resilience is an emerging concept that is increasingly used to represent the durability and stable performance of energy systems against extreme climate ***,it has not yet been adequately explored and widely used,as its definition has not been clearly articulated and assessment is mostly based on qualitative *** study reveals that a major limitation in the state-of-the-art is the inadequacy of climate change adaptation approaches in designing and preparing urban energy systems to satisfactorily address plausible extreme climate ***,the complexity of the climate and energy models and the mismatch between their temporal and spatial resolutions are the major limitations in linking these ***,few studies have focused on the design and operation of urban energy infrastructure in terms of climate *** the occurrence of extreme climate events and increasing demand for implementing climate adaptation strategies,the study highlights the importance of improving energy system models to consider future climate variations including extreme events to identify climate resilient energy transition pathways.

关键词： climate resilience climate change adaptation urban energy systems renewable energy extreme events decentralized generation

The role of radiotherapy in metastatic bladder cancer

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Journal of Cancer Metastasis and Treatment 2022年第1期8卷 553-563页

作者： Jananie perera Peter Hoskin Mount Vernon Cancer Centre Rickmansworth RoadNorthwoodMiddlesex HA62RNUK Division of Cancer Sciences University of ManchesterManchester M204GJUK

The management of metastatic bladder cancer is *** outcomes are achieved in those who are fit enough for systemic *** place of radiotherapy in these patients is mainly for symptom control,in particular ***,a small proportion,especially those with oligometastases,will benefit from more radical *** this review,we look at the evidence currently available for radiotherapy in this setting.

关键词： Bladder cancer radiotherapy oligo metastases haematuria bone metastases brain metastases

Ship performance and navigation data compression and communication under autoencoder system architecture

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Journal of Ocean Engineering and Science 2018年第2期3卷 133-143页

作者： Lokukaluge P.perera B.Mo UiT The Arctic University of Norway TromsoNorway SINTEF Ocean TrondheimNorway

Modern vessels are designed to collect,store and communicate large quantities of ship performance and navigation information through complex onboard data handling *** data should be transferred to shore based data centers for further analysis and ***,the associated transfer cost in large-scale data sets is a major challenge for the shipping industry,*** same cost relates to the amount of data that are transferring through various communication networks(*** and wireless networks),*** vessels and shore based data ***,this study proposes to use an autoencoder system architecture(i.e.a deep learning approach)to compress ship performance and navigation parameters(*** the number of parameters)and transfer through the respective communication networks as reduced data *** data compression is done under the linear version of an autoencoder that consists of principal component analysis(PCA),where the respective principal components(PCs)represent the structure of the data *** compressed data set is expanded by the same data structure(*** autoencoder system architecture)at the respective data center requiring further analyses and storage.A data set of ship performance and navigation parameters in a selected vessel is analyzed(*** compression and expansion)through an autoencoder system architecture and the results are presented in this ***,the respective input and output values of the autoencoder are also compared as statistical distributions and sample number series to evaluate its performance.

关键词： Autoencoder Ship performance and navigation information Ship energy efficiency Data compression Data communication Principal component analysis